The invention relates to a hardening furnace, in particular for sheets of glass and the like.
The prior art embraces hardening furnaces equipped with a conveyor plane, generally having motorized rollers, which plane supports the sheets of glass, transports them and alternates the movement direction.
In such realizations, thermal energy is transferred to the sheets of glass usually by radiation by means such as electric resistance, radiating plates, always electrically powered, arranged above and below the conveyor plane in such a way as to cover the entire surface of both sides of the sheet of glass completely. An appropriate distribution of the means of radiation, combined with regulation of the energy source, permits regulating and dosing the flow of energy which hits, moment by moment, each point or zone of the surface occupied by the said conveyor plane on which the sheets of glass are moved. In particular, this permits dosing the energetic flow hitting the sheets of glass crossing the furnace both in longitudinal and in transverse directions in such a way as to realize uniform heating of the same sheets of glass. The possibility of control of the flow distribution on the conveyor or work plane, which depends essentially on the relative ease of regulation permitted by the electric energy source, permits treating, without drawbacks, loads of glass sheets which differ in size and dimensions both in tranverse and in longitudinal directions.
Such prior art realizations, with electric energy sources, are characterized by high energy costs.